1. Field of the Invention
The invention relates to a system for inspecting parameters of leads on quad flat-pack (QFP) chip packages. The invention also relates to a method for inspecting these parameters using the inventive system.
2. Description of Prior Art
Large QFP chip packages have many (sometimes hundreds) of "gull wing" type leads on their perimeter. As technology advances, the size of these leads and clearance between them becomes smaller and smaller. It is necessary for all of the leads to have proper clearance. It is also necessary that the leads should not be bent out of shape, and that the leads should be coplanar, that is, when placed on a flat surface (for example a printed circuit board) all leads should either be touching the flat surface or have a minimum clearance which will still allow for proper soldering of the leads to the surface. Devices with out of specification leads can not be properly soldered resulting in higher manufacturing cost and, if not detected early, even costlier failures in the field.
To prevent damage of the very fragile leads, a dozen or more devices are packaged and shipped in special trays. These trays support the plastic or ceramic bodies, from whose periphery the leads extend, to leave the lead tips without any contact or strain.